Disposable reserve activated electrochemical cell

ABSTRACT

A disposable reserve activated electrochemical cell wherein the active elements of the cell, including electrolyte solvent, are maintained in a separate first flexible plastic envelope and the entire cell, including the first envelope, are contained within a second flexible plastic envelope. Both the first and the second envelope are contained within a relatively rigid housing. The activation of the cell is achieved by perforating the first envelope, without breaking the seal of the second envelope, thereby maintaining a good hermetic seal and preventing leakage.

United States Patent [191 Weidner 1 Jan. 30, 1973 [54] DISPOSABLERESERVE ACTIVATED ELECTROCHEMICAL CELL Evert C. Weidner, Philadelphia,Pa.

Assignee: Honeywell Inc., Minneapolis, Minn.

Filed: Aug. 30, 1971 Appl. No.: 175,825

Inventor:

US. Cl ..l36/I13, 136/90 Int. Cl. ..II0lm 21/00 Field of Search ..l36/l12-1 14, 90, 136/160, 162-163; 137/260; 141/302;

References Cited UNITED STATES PATENTS 9/l967 Andersson ..l36/90 ll/l969Merz et al. ..l36/9O Orsino ..l 36/1 13 Winckler ..l 36/1 13 PrimaryExaminer-Anthony Skapars Attorney-Charles J. Ungemach et al.

[57] ABSTRACT 5 Claims, 3 Drawing Figures PATENIEBmao ms 3.713.894

FIG.I

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w 2 6 BY F G 3 AITTORNEY DISPOSABLE RESERVE ACTIVATED ELECTROCHEMICALCELL BACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention relates to reserve activated primary electriccurrent-producing cells. More particularly, the invention relates to thetype of cells wherein a liquid electrolyte solvent, by itself or incombination with other active elements, is utilized and is confinedprior to activation in a manner to prevent its simultaneous contact withthe cell anode and the cell cathode.

2. Description of the Prior Art Prior art is replete with designs forreserve activation of electrochemical cells. Most of the prior artdesigns, however, are relatively expensive to construct. Others, lessexpensive to make, have shortcomings, such as leakage and short shelflife, which-the present invention eliminates.

An example of such prior art devices is described in U.S. Pat. No. 2,118,996, wherein an emergency lamp is shown with reserve activationcapability. The electrolyte is maintained in a spherical glass ampulewhich may be broken when activation is desired. Another example of priorart is U.S. Pat. No. 3,343,993, also relating to a deferred action cellin which the electrolyte is maintained in a separate compartment priorto activation. Means are provided for transferring the electrolyte fromthe electrolyte compartment to the cell compartment for activation..

SUMMARY OF THE INVENTION A reserve activated primary electriccurrent-producing cell according to the present invention will find usewherever reserve power maybe needed after. long periods of inactivelife. For example, it could find use in the area of civil defense'or inemergency kits for automobiles, boats, camping equipment of the like.

The improvement of the present invention over prior art lies in thedouble envelope structure which provides a secure hermetic seal witheasy and inexpensive construction. The outside housing of a cellaccording to the present invention is in the form of an elongated rigidplastic cylinder. The housing has an open slot at one (rearward) end anda pair of electrical conductors extending through the housing at theother (forward) end. Located centrally along the axis within thishousing is a first flexible plastic envelope containing activeelectrochemical material. This first envelope is sealed to maintain itscontents out of contact with all other components within the housing.The other components within the housing include an anode, a suitableseparator surrounding the anode, and a cathode collector. All of theseother components, as well as the first flexible envelope with itscontents, are contained within a second elongated flexible plasticenvelope having one open end. The open end of the second envelope'ismounted within the housing against the forward end in such a way thatthe electrical conductors extend into the second envelope for connectionto the anode and the cathode collector. The seal between the open end ofthe envelope and the housing is hermetic. The second plastic envelope issubstantially longerthan the housing and is folded up in a telescopingmanner to conform with the housing dimensions. The end of the secondenvelope opposite to its open end extends partially through the slot inthe outside housing os that it can be grasped between two fingers andpulled outwardly for some distance without breaking the seal. Internallyto the second envelope, one end of the first envelope is attached to thesecond envelope at the end opposite to the open end and extendingoutwardly through the slot in he housing and through this attachment,the second envelope is hennetically sealed. In this way, a pullingaction on the first envelope will result in pulling of the secondenvelope with it. Pulling of the second envelope results in the motionof the first envelope through the slot, causing it to be perforated bythe internal frame. At the same time, the seal of the second enveloperemains undisturbed since, due to the extended length of the secondenvelope, it results in only unfolding of the telescoped section.Leakage of the cell contents through the open slot is thereby prevented.

The two electrical conductors extending through the end of the housingopposite to the open slot are connected internally to the cathodecollector and the anode, respectively. Externally they are connected toan electric light bulb or other electric current-operated device. H

The design of the present invention is ideally suited to allow simplestep-by-step assembly in an automated production facility.

It is therefore an object of the presentinvention to provide animprovedand relatively inexpensive reserve activated electric current-producingcell.

A further object of the present invention is to provide a disposablereserve flashlight. I

These and further objects will become apparent to those skilled intheart upon consideration of the following specification, claims, anddrawing.

BRIEF DESCRIPTION OF THE DRAWING.

FIG. 1 illustrates a preferred embodiment of a reserve activated cellaccording to the present invention prior to activation;

, FIG. 2 illustrates the preferred embodiment of the invention of FIG. 1after activation; and

FIG. 3 illustrates an alternate embodiment of the present invention.

DESCRIPTION THE PREFERRED EMBODIMENT Referring now to FIG. 1, adisposable reserve flashlight is illustrated having an external housing10 constructed of relatively rigid plastic material. For con venience,the housing has an elongated cylindrical shape, but this is only choiceof design. Housing 10 has a forward end 11, through which a pair ofelectrical conductors 20 and 21 extend, passing from the outside to theinside of housing 10. Housing 10 has a second rear end 12 provided withan open slot 14. The length of slot 14 extends across substantially theentire cross section of end 12 and is of sufficient width to allowpassage of several thicknesses of polyethylene filmQAt forward end 11 ofhousing 10, conductors 2 0 and 21 are connected externally to anelectric light bulb 24.

Within housing 10, a quantity of active cathode materialtogether with anelectrolyte solution identified as 25, is contained within a flexibleplastic envelope 26. Envelope 26 is, in the preferred embodiment,constructed of polyethylene or other heat sealable film. Its dimensionsare roughly in conformance with the cross sectional longitudinalinternal dimensions of housing 10. Also within housing 10, on one sideof envelope 26, is positioned a cathode collector 27. Cathode collector27 is of rectangular flat shape essentially equal in size to envelope 26and may be constructed of an expanded or perforated sheet of nickel orother conductive material compatible with the particularelectrochemistry of the system. On the other side of envelope 26, withinhousing 10, is positioned an anode 28 enclosed within a sleeve ofseparator material 39 approximately equal in dimensions to cathodecollector 27 and envelope 26. The anode may be constructed of thinmagnesium sheet or other anode suitable material. In the preferredembodiment, the anode is sandwiched between two layers of heat scalableporous separator material. Anode 28 is connected to the internal end ofconductor 21, while cathode collector 27 is connected to the internalend of conductor 20.

The entire assembly, including anode 28, envelope 26 -and its contents,and cathode collector 27 are enclosed within a second envelope30 havingan open end. Envelope 30 has its open end attached internally to forwardend 11 of housing 10, forming a hermetic seal at 31. In the preferredembodiment shown, envelope 30, when extended, has a longitudinaldimension equal to approximately twice the length of housing 10. To fitwithin housing 10, envelope 30, is folded in a telescoping fashion (asshown at 32) around the cell elements with the end of envelope 30nearest rear end 12 of housing protruding partially outwardly throughslot 14. The outward protrusion of envelope 30 is identified by numeral36. The outward protrusion 36 through slot 14 is of sufficient length toprovide a convenient surface for grasping and pulling envelope 30outwardly. The end of envelope 26 nearest rear end 12 of housing 10 isattached firmly (heat sealed) to the internal surface of envelope 30'at34, fusingthe four layers togetherpAt the other end of envelope 26 ismounted a perforating point 35, designed to engage envelope 26 and causeit to rupture when relative motion is produced. Perforating point 35 ispart of a frame 38 of sufficient thickness and rigidity not to be ableto pass through slot 14. I

Activation of the cell is achieved by pulling outward protrusion 36 ofenvelope 30 through slot 14. This pulling action results in motion ofenvelope 26 past perforating point 35, resulting in rupture of envelope36. By pulling envelope 30 outwardly to its full extension,

the walls of envelope 26 are removed from the area between the cellactive material 25 and the anode on one side, and material 25 andcathode collector on the other side. The cell elements are brought intoelectrochemical contact through the action of the electrolyte which isreleased from envelope 26 and allowed to freely flow between the cellelements. To prevent escape of the contents of envelope 26 through slot14 with the motion of envelope 26, a rigid stop member (frame) 38 isinterposed between active material 25 and the end of envelope 26 nearestslot '14. Stop member 38 has dimensions'exceeding the slot opening andis shaped to allow envelopes 26 and 30 to slide around it as they arepulled through slot 14. A cell in its activated state is illustrated inF IG. 2.

The primary function of envelope 30 is to prevent leakage of fluidsthrough slot 14 after envelope 26 is perforated. Thus, the design ofenvelope 30 can vary considerably without departing from the concept ofthe present invention. For example, the open end of en-v velope 30 couldbe attached to the rear inside end of housing 10, as shown in FIG. 3,assuming that housing 10 is itself constructed of material capable ofmaintaining a hermetic seal. In such case, envelope 30 would need beonly about half as long as that shown in the embodiment of FIG. 1.

In an embodiment, successfully demonstrating the feasibility of thepresent invention, the following composition was employed. The anode wasconstructed of magnesium, the cathode collector comprised of an expandednickel screen, a paper separator was wrapped around the anode, thecathode composition comprised of 68.4 percent manganese dioxide and 31.6percent carbon mix, and the electrolyte comprised a solution of lithiumchloride in water. The overall dimensions of the cell were inch by inchby 4 inches. Upon activation, the cell demonstrated a useful output lifeof 15 to 20 minutes. I

An extended shelf life for the cell of the present invention isguaranteed by separation within bag 26 of the electrolyte solution or acombination of the cathode material and the electrolyte. Leakage of thecell 'chemicals'g is prevented after activation by the second envelope;

Clearly, modifications and alterations can be made to the design of thedisclosed invention without departing from the spirit of the invention.For example, further reduction of unit cost can be achieved by enclosingtwo or more reserve cells within a single housing, connected inparallel. The cells could then be activated consecutively with orwithoutstorage interval.

I claim:

1. A reserve activated primary cell comprising:

a housing having an open slot at one end;

a first flexible hermetically sealed envelope positioned within saidhousing;

active electrochemical material contained within said first envelope;

a second flexible hermetically sealed envelope positioned within saidhousing and containing said first envelope;

said second envelope further containing elements of electriccurrent-producing cells which together with v the electrochemicallyactive material contained within said first envelope constitute acomplete electric current-producing cell;

means extending through said open slot, attached to said second envelopefor pulling said second envelope; and

means for perforating said first envelope in response to the pulling ofsaid second envelope without breaking the seal of said second envelope.

2. A reserve activatedprimary cell comprising:

a substantially rigid outside housing having an opening therein;

cell components positioned within said housing;

a first hermetically sealed flexible envelope surrounding one or more ofsaid cell components, keeping them out of electrochemical contact withother cell components, thereby rendering the cell inactive;

a second flexible envelope of non-porous material positioned within saidhousing and enclosing said first envelope and said cell components, saidsecond envelope having a first end attached to the internal wall of saidhousing to form a seal between said cell components and said opening insaid housing, and having a second end protruding through said opening,said second envelope further being of sufficient length so that it maybe pulled through said opening for a given distance without breakingsaid seal;

said first envelope being attached to said second envelope such that apulling action on said second envelope through said opening results inpulling along of said first envelope; and

means mounted within said housing for engaging and perforating saidsecond envelope when said first envelope is moved relative thereto.

3. A reserve activated primary cell according to claim 2 wherein saidfirst and said second envelopes are constructed of heat sealable film.

4. A reserve activated primary cell according to claim 3 wherein saidheat sealable film is polyethylene.

5. A reserve activated primary cell according to claim 2 wherein saidsecond envelope is folded in a telescoping manner prior to being pulledthrough said opening in said housing.

1. A reserve activated primary cell comprising: a housing having an openslot at one end; a first flexible hermetically sealed envelopepositioned within said housing; active electrochemical materialcontained within said first envelope; a second flexible hermeticallysealed envelope positioned within said housing and containing said firstenvelope; said second envelope further containing elements of electriccurrent-producing cells which together with the electrochemically activematerial contained within said first envelope constitute a completeelectric current-producing cell; means extending through said open slot,attached to said second envelope for pulling said second envelope; andmeans for perforating said first envelope in response to the pulling ofsaid second envelope without breaking the seal of said secondenvelope.
 1. A reserve activated primary cell comprising: a housinghaving an open slot at one end; a first flexible hermetically sealedenvelope positioned within said housing; active electrochemical materialcontained within said first envelope; a second flexible hermeticallysealed envelope positioned within said housing and containing said firstenvelope; said second envelope further containing elements of electriccurrent-producing cells which together with the electrochemically activematerial contained within said first envelope constitute a completeelectric current-producing cell; means extending through said open slot,attached to said second envelope for pulling said second envelope; andmeans for perforating said first envelope in response to the pulling ofsaid second envelope without breaking the seal of said second envelope.2. A reserve activated primary cell comprising: a substantially rigidoutside housing having an opening therein; cell components positionedwithin said housing; a first hermetically sealed flexible envelopesurrounding one or more of said cell components, keeping them out ofelectrochemical contact with other cell components, thereby renderingthe cell inactive; a second flexible envelope of non-porous materialpositioned within said housing and enclosing said first envelope andsaid cell components, said second envelope having a first end attachedto the internal wall of said housing to form a seal between said cellcomponents and said opening in said housing, and having a second endprotruding through said opening, said second envelope further being ofsufficient length so that it may be pulled through said opening for agiven distance without breaking said seal; said first envelope beingattached to said second envelope such that a pulling action on saidsecond envelope through said opening results in pulling along of saidfirst envelope; and means mounted within said housing for engaging andperforating said second envelope when said first envelope is movedrelative thereto.
 3. A reserve activated primary cell according to claim2 wherein said first and said second envelopes are constructed of heatsealable film.
 4. A reserve activated primary cell according to claim 3wherein said heat sealable film is polyethylene.